Yes, a step back. The Bills were doing very well last year before some major injuries to Fitz, Jackson, etc. They may have been the most injured team in the league. They have a lot of good, young players on that roster, and I think, with all the cap room, they could have upgraded a lot of positions and put themselves in wild card contention. Now, I just see them as one poor player performance away from 4-12.
In terms of whether we'd be happy if we got M Williams, of course. He is a very good player, maybe even elite. I don't think there's a single Pats fan who wouldn't have wanted him. But here is where you once again fall short in the reasoning department: this is about return on investment, and Williams will almost certainly not deliver a positive ROI. His contract would only be justified if he is much better than he's been previously, and more likely, that $20M per season was not a good move.
The Bills OUTBID the other teams for Mario Williams. This wasn't a victory by any means. If the Patriots had called Williams on Wednesday and offered him $25M, do you really think Pats fans would be justifiably beating their chests, boasting about how they just made a huge coup? What if the Panthers then went up to $30M per season? Are they then the smartest team? This is the whole point, at some time you've gone insane by giving up too much for one player on a team with 53 players. This isn't the NBA where one guy can win a championship or MLB where teams have unlimited payrolls.
I would say that, so far, this is one of the worst free agency moves of the year. There are very few free agency moves that work out, but usually they are done quietly and require the recognition of value and a high risk:reward ratio. In this case, it is very high risk with the slight possibility of high reward, but for Williams to actually outperform his contract, he'd have to be Lawrence Taylor in his prime, which he's not. Why is this so difficult to understand?